Thermostat.



J. J. WOOD- THERMOSTAT. APPLICATION man JUNE 25. 1914.

Patented July 4, 1916.

Wi messes: lnve'nto r": M! 734%- Ja rnes J.Wood,

His fitter-neg.

UNITED STATES PATENT OFFICE.

JAMES J. WOOD, 0F FORT WAYNE," INDIANA, ASSIGNOR T0 GENERAL ELECTRICCOM- IPAN'Y, A CORPORATION OF NEW YORK.

THnnMostrAr.

Specification of Letters Patent.

Patented July 4, 1916..

Application filed June 25, 1914. Serial No. 847,340.

To all whom it may concern:

Be it known that 1, JAMES J. Wooo, a citizen of the United States,residing at Fort Wayne, county of Allen, State of Indiana, haveinvented'certain new and useful 1mprovements in Thermostats, of whichthe following is a specification.

My invention relates to thermostats, and particularly to the improvedconstruction and arrangement of the parts constituting such aninstrument.

In instruments of this character, especially where they are designed to,operate on circuits of a considerable voltage, it is desirable that theopening and closing of the circuit should be positive and quick in orderto prevent arcing at the contacts, and that the instrument should besensitive and readily adjustable. v

My object has been, therefore, to produce an instrument which willoperate in the manner outlined above, and at the same time will becompact, strong, accessible, and in member-distinct from but connectedwith the general an eflicientinstrument.

Another object of my invention'is to provide a thermostat having amovable contact thermostatic element and to provide a novel suspensionfor this member. v Still another object isto provide anti-friction.bearin'gs for the movable contact member mentioned above.

Further objects of my invention will appear from the detaileddescription and the claims appended thereto.

Briefly, my thermostat comprises a sup? porting plate carrying 'acentrally arranged stud. to which one end of a spirally coiled springwhich constitutes a thermostatic element is connected. Over-lying thisspring and oscillating across a vertical axis is aconv tact arm or barpivoted at its lower end} on a stationary bearing. The free end of; thespring is pivotally connected to this bar just above the stationarybearing and when it contracts or expands, di1e to changes. intemperature, moves the barto one side. or the other of the vertical.'The spring and stationarj bearing constitute a' suspension for thecontact. bar. Preferably, the" contact bar is engagedby. one, of thesehearings at two separated points and by the other at an intermediatepoint, thus forming a three point suspension, Bothof the elements. of

with the contact springs are stops limiting the movement of the contactarm. At the rear end of the stud which supports the thermostaticelement, a worm and gear adjusting means is provided for adjusting theinstrument so that it will operate at the desired temperature.

One of the many applications of my device is to refrigerating machines.an arrangement the contacts will be arranged to close a circuit toenergize the coil of an electromagnetically operated switch when thecontact arm moves to the left, for instance, and when it moves to theright will form a short circuit around this same coil, thereby takingcare of the inductive kick.

I have, more fully described my invention In such g Figure 1 is a frontelevation with the cover I removed; Fig.2 is a side elevation, lookingat the left of Fig. 1, showing the. cover in section; Fig. 3 is a topview with the cover in section; Fig. 4 is a detail showing the Worm andgear adjusting means; and'Fig. 5

is a diagrammatic view showing the circuits when the thermostat isconnected in the manner suggested above.

A supporting plate 10,- preferably lar, is supplied with legs ll bywhich it isintended that it shall be attached to a vertical surface.These legs are offset in such a way that the supporting'plate is heldout from the surface to which" the instrument is applied, in order toaccommodate certain parts projecting from the back of the plate.

It will be noted also that thesupporting legs project beyond the outercircumference of the plate, so that the instrument may be the plate aworm gear 14 is applied to this.

stud and secured by means of a nut 15. For

the purpose of adjusting this stud to any desired position, a worm 17 issupported by a stud 16 in operative relation with the gear 14. This wormis provided with a slotted head 18 projecting'beyond theoutercircumference of the supporting plate, whereby it may be easilyturned.

The forward end of the stud 12 is slotted to admit one end of'athermostatic element formed as a spiral spring 20. This spring willrespond to changes in temperature by expanding or contracting, and ispreferably constructed in the usual manner out of two elements havingdifferent coefficients of expansion. As will be seen in Fig. 2, theouter end of the spring is reduced in width at 21 and provided with aslot 22 for a purpose to be later explained. This reduced end" is turnedat practically right angles i with the main portion of the spring and is20 sharpened to provide a knife edge for engagement w1th apivotedcontact arm, as shown in dotted lines in Fig. 1. This contact blade orbar 30 is a U-shaped member whose central portion overlies the spring20and whose legs 37 and 33 project inwardly above and below this spring.The lower leg 33 is provided with a'V-shaped groove on ts upper edge inwhich the sharpened edge of thespring 20 engages (see Fig. 1). Adjacentthe ends of this leg are depending feet 34 providedwith an upwardlyextending V-shaped groove. These grooved feet rest upon a stationaryhearing in the form of a knife edge 32 held. in a stud 31 attached tothe supporting plate. At approximately the center of the lower leg 33 apin 35 is provided, which projects into the slot 22 .and preventsdisplacement of the end of the spring in the groove. The upper leg 3'1is provided on its upper side, adjacent the end,

with a contact piece 38 which may be constructed of silver or any othernon-corrosive conductor. 7

The pivoted contact arm 30 cooperates at its upper end with fixedcontacts held in binding posts 40 and 40. The binding posts pass throughapertures in the supporting plates 10 larger than the posts and arefixed in metal plates 41 suitably insulated from the plate 10 by meansof pieces of insulation 42, the whole being held in position by means ofinsulated screws. Ad-

jacent their 'outer'ends, the binding posts 40 and 40 are slotted toreceive spring con tact members 43, which are slitted, as will be seenfrom Figs. 2 and 3, and are provided .at the lower side of their freeends with contacts 44 which maybe constructed of silver or a similarmetal. Supported upon the posts 40 and 40, at a point inside the springcontacts, are fixed stops 45 which venient point a third binding post 46is electrically connected with the plate 10 and thereby, through themembers 31 and 32, with the contact arm 30.

The instrument is preferably, provided with a cover 5 0 fitting in agroove 54 in the plate 10 and held in place by screws 51. This cover isprovided with a transparentclosure 52. 4

The instrument may be applied to any device in which it is desired toopen and close a circuit in response to changes in temperature. Onemanner of application is illustrated in Fig. 5. Here the mains 6O supplyenergy from a source of power (not shown). If the contact arm 30,electrically connected through the supporting plate with the bindingpost 46, is moved to the left until it touches the spring attached tobinding post 40, then the operating coil 61 of an electromagneticallyoperated switch will be energized from the mains and the contacts 62,forming the terminals of any desired circuit, will be closed. Inthepreferred arrangementof my invention, the binding post 40 is connectedto one terminal of the circuit which was closed, here one terminal ofthe coil 61, in such a manner that when the contact arm 30 touches thespring attached to the. binding post 40, the inductive portion of thecircuit, here the coil 61,- isshort-circuited. Because of the particulararrangement of the parts, as later explained, the time interval betweenthe opening of the circuit and the closing of the short circuit is verysmall, and any are which may be formed by the opening of the inductivecircuit will be quickly extinguished. p I

It will be seen from an inspection of Fig. 1, that the contact armfrictionally engages thespring contacts 43 in such a way that somelittle pull is required to disengage the I the desired mean, before thearm 30 will be pulled over by the spring 20 from one spring contact 43to the other, and that a considerable torque will have been therebydeveloped which will insure positive and quick action both in openingthe short circuit and in energizing the other clrcuit. By means of theparticular relations of the various elements, it will be seen that I amenabled to make my temperature responslve spring 20 of considerablewidth, and that as a result the torque developed thereby will becomparatively large. It should be further noted that the contact armoscillates about a vertical plane through the knife edge 32,. and that,therefore, it cannot readily find a position of stable equilibriumbetween the two spring contacts. Further,

- the particular relation of the feet 34 and the reduced end 21 of thespring constitutes a three-point suspension for the contact arm, thepoints of engagement being provided with anti-friction bearings.By-means of the head 18 and the cooperating worm and gear, the stud 12may be readily adjusted to any, desired position, thereby adjusting thetension of the spring so that it will respond to any desiredtemperature.

I conceive that various modifications of the details of the particulararrangement which I have shown. may be made, and I, accordingly, do notdesire to be limited to the exact construction shown other than as I amlimited by the terms of the appended claims, but I wish it understoodthat my invention extends not only to the broad gen-.

by Letters Patent of the United States, is,

1. A thermostatic switch comprising a movable contact bar having a legextending at right angles thereto, a stationary support pivotallyengaging with one side. of said leg, a coiled thermostatic elementpivotally engaging with the opposed side of said leg, one of saidcoactingbearings engaging with said legat'two pointsand the otherengaging at an intermediate point, and a fric- I tional contact", oneach sidev of said contact 'bar to engage";- with and temporarily holdsaid contact bar. F

24A thermostat comprising a horizontal knifeedge support, a movablecontact arm provided with a V -shaped groove resting upon said supportand extending upwardly therefrom, said arm being provided with another V-shaped groove above the firstnamed groove, means responsive to changesin'temperature having a moving part resting in said uppergroovefand afixed contact cotiperating with the upper end of said 3. thermostatcomprising 'a flat supporting plate adapted to be arranged in a verticalplane, a knife-edge support perpenv stud and having its free endnormally adjacent to and above said support a fixed contact, a movablecontact arm cooperating therewith, saidfarm having an offset leg at 7its lower end, said leg having a V-shaped groove in its upper sidereceiving the free end of said thermostatic element intermediate theends of the'leg, feet adjacent the ends of said leg having a lI-shapedgroove on their lower edges and bearing on said knife-edge support.

4. A thermostat comprising a flat supporting plate adapted to bearranged in a vertical plane, a contact arm pivoted to said plate at itslower end and arranged so that its upper end oscillates across aperpendicular axis through the pivot point, thermostatic means connectedto said arm for moving the same, binding posts insulated from each.other and said arm attached to said plate on opposite sides of said axisadjacent the upper end of said arm, and contact springs carried by saidposts curved to frictionally engage and temporarily retain said arm incontact therewith.

5. A thermostat comprising a flat supporting plate adapted tobearrangedin a vertical plane, a contact arm pivoted to said plate at its lowerend and arranged so that its upper end oscillates across a perpendicularaxis through the pivot point, thermostatic means connected to said armfor mov-' ing the same, binding posts insulated from each other and saidarm attached to said plate on opposite sides of said axis adjacent theupper end of said arm, contact springs carried by said posts curved tofrictionallya vertical support, a substantially centrally arrangedrotatable stud carried by said plate, a worm gear on said stud behindsaid plate, a worm for rotating saidgear, a spirally coiled spring infront of said plate having its inner end attached to said stud, a[Ll-shaped contact arm having its central portion overlying said springin an approximately vertical position, means'for p1vot-.

ally supporting the lower leg of said contact arm at points adjacent itsends, said leg be- "ing provided with a V-shaped groove in its upper,side, the outer end of said spring being reduced in width and sharpenedto en: gage said groove intermediate the ends of said leg, flexiblecontacts supported by but insulated from said plate at each side of andabove'said spring and cooperating with the upper leg of said arm tofrictionally engage the same, and stops adjacent said contacts.

7. A thermostatic switch comprising a movable contact bar having a legextending at right angles thereto, a thermostatic ele-" menthaving aknife edge bearing upon the leg to move the contact bar, and a similarstationary bearing for the contact bar cooperating with the bearing ofthe thermo' static element to constitute a suspension for anti-frictionbearing upon one oflset leg to set leg of the contact bar opposite saidoperate the same, a similar stationary bearbearings. I d 10 ing for themovable bar, one of said bear- In Witness whereof, I have hereunto setings having two points of engagement, and my hand this 22nd day of June,1914.

the other a single point between the two L JAMES J. WOOD. points,thereby forming a three-point sus Witnesses: pension for the bar, andone or more fixed H. E. CRANE,

contacts frictionally engaging with the ofi'- A. L. HADLEY.

